10.6 Ex-situ Solid Phase and Vapor Phase

1. 10.6 Ex-situ Solid Phase and Vapor Phase http://www.frtr.gov/matrix2/top_page.html Materials are taken from the Textbook: Hazardous Waste Management. 2nd Ed. Legrega et al., McGraw Hill

2. Ex-situ Solid/Vapor Phase • Land treatment • Composting • Soil piles (Biopiles) • Land farming

3. Biopiles Biopile treatment is a full-scale technology in which excavated soils are mixed with soil amendments and placed on a treatment area that includes leachate collection systems and some form of aeration. It is used to reduce concentrations of petroleum constituents in excavated soils through the use of biodegradation. Moisture, heat, nutrients, oxygen, and pH can be controlled to enhance biodegradation. http://www.frtr.gov/matrix2/section4/4_11.html

4. Composting http://www.frtr.gov/matrix2/section4/4_12.html

5. Land farming Land farming is a full-scale bioremediation technology, which usually incorporates liners and other methods to control leaching of contaminants, which requires excavation and placement of contaminated soils, sediments, or sludges. Contaminated media is applied into lined beds and periodically turned over or tilled to aerate the waste. http://www.frtr.gov/matrix2/section4/4_13a.html

6. Slurry Phase Biological Treatment Slurry phase biological treatment involves the controlled treatment of excavated soil in a bioreactor. The excavated soil is first processed to physically separate stones and rubble. The soil is then mixed with water to a predetermined concentration dependent upon the concentration of the contaminants, the rate of biodegradation, and the physical nature of the soils. Some processes pre-wash the soil to concentrate the contaminants. Clean sand may then be discharged, leaving only contaminated fines and washwater to biotreat. Typically, a slurry contains from 10 to 30% solids by weight. http://www.frtr.gov/matrix2/section4/4-14.html

7. Land treatment

8. Assimilative capacity • Capacity limiting • Conservative • Rate limiting • Non-conservative • Application limiting • Transport

9. 9

12. Composting • Aeration • Windrows • Static piles • Enclosed reactors • An-aerobic/aerobic

14. 10 Accepting the equation 10-16, it can be used to determine the degradation rate constants.

23. Enhanced Bioremediation • Typical Oxygen-Enhanced Bioremediation System for Contaminated Ground water with Air Sparging • Oxygen-Enhanced H2O2 Bioremediation System • Typical Nitrate-Enhanced Bioremediation System  

24. Enhanced Bioremediation

25. Oxygen Enhancement with Air Sparging • Air sparging below the water table increases ground water oxygen concentration and enhances the rate of biological degradation of organic contaminants by naturally occurring microbes. • Air sparging also increases mixing in the saturated zone, which increases the contact between ground water and soil. • The ease and low cost of installing small-diameter air injection points allows considerable flexibility in the design and construction of a remediation system. • Oxygen enhancement with air sparging is typically used in conjunction with SVE or bioventing to enhance removal of the volatile component under consideration.

26. Oxygen Enhancement with Hydrogen Peroxide • During hydrogen peroxide enhancement, a dilute solution of hydrogen peroxide is circulated through the contaminated ground water zone to increase the oxygen content of ground water and enhance the rate of aerobic biodegradation of organic contaminants by naturally occurring microbes.

27. Nitrate Enhancement • Solubilized nitrate is circulated throughout ground water contamination zones to provide an alternative electron acceptor for biological activity and enhance the rate of degradation of organic contaminants. • Development of nitrate enhancement is still at the pilot scale. • This technology enhances the anaerobic biodegradation through the addition of nitrate. • Fuel has been shown to degrade rapidly under aerobic conditions, but success often is limited by the inability to provide sufficient oxygen to the contaminated zones as a result of the low water solubility of oxygen and because oxygen is rapidly consumed by aerobic microbes. • Nitrate also can serve as an electron acceptor and is more soluble in water than oxygen. • The addition of nitrate to an aquifer results in the anaerobic biodegradation of toluene, ethylbenzene, and xylenes. • The benzene component of fuel has been found to biodegrade slower under strictly anaerobic conditions. • A mixed oxygen/nitrate system would prove advantageous in that the addition of nitrate would supplement the demand for oxygen rather than replace it, allowing for benzene to be biodegraded under microaerophilic conditions.